A compression encoding means a series of signal processing techniques for transmitting digitized information through a communication line or techniques for storing the information in a form that is proper for a storage medium. The media including a picture, an image, an audio, and the like may be the target for the compression encoding, and particularly, the technique of performing the compression encoding targeted to the picture is referred to as a video image compression
The next generation video contents are supposed to have the characteristics of high spatial resolution, high frame rate and high dimensionality of scene representation. In order to process such contents, drastic increase of memory storage, memory access rate and processing power will be resulted.
Accordingly, it is required to design the coding tool for processing the next generation video contents efficiently.
In particular, a graph is a data expression form advantageous for describing inter-pixel relation information, and a graph-based signal processing scheme of processing inter-pixel relation information by expressing it as a graph has been utilized. In the graph-based signal processing, concepts such as sampling, filtering, conversion, and the like, may be generalized using a graph in which each signal sample indicates a vertex and relations of signals are indicated as graph edges having a positive weight.
In general, a separable discrete cosine transform is used when encoding a residual signal. A major problem of the separable DCT is that the separable DTC is based on an ambiguous assumption that every residual signal has isotropic statistical properties. However, in actuality, residual blocks may have very different statistical properties according to a prediction method and video content. Thus, it is required to enhance compression efficiency using different transform adaptive to statistical properties of residual blocks.